There are variable valve mechanisms 90a, 90b, 90c of first to third conventional examples shown in FIGS. 8 to 10. Each of the variable valve mechanisms 90a, 90b, 90c is configured as follows. Each of the variable valve mechanisms 90a, 90b, 90c includes an input member 92, an output member 93, a slider 94, and a variable device 97. When driven by a cam 91, the input member 92 swings about a predetermined axis x in the circumferential direction of the axis x (swing direction P, Q). The output member 93 swings together with the input member 92 to drive a valve 6. The slider 94 can be displaced in the longitudinal direction of the axis x (thrust direction L, R) relative to the input member 92 and the output member 93. When displaced in the thrust direction L, R relative to the input member 92 and the output member 93, the slider 94 turns the output member 93 in the swing direction P, Q relative to the input member 92 to change the valve lift amount. The variable device 97 displaces the slider 94 in the thrust direction L, R relative to the input member 92 and the output member 93. A specific configuration of each variable valve mechanism 90a, 90b, 90c is as follows.
The variable valve mechanism 90a of the first conventional example (Patent Document 1) shown in FIG. 8 includes two output members 93, 93 on both sides in the thrust direction L, R of the input member 92. The two output members 93, 93 drive two valves 6, 6.
The variable valve mechanism 90b of the second conventional example (Patent Document 2) shown in FIG. 9 includes the output member 93 only on one side in the thrust direction L, R of the input member 92. The variable valve mechanism 90b further includes a drive portion 93b below the output member 93. The drive portion 93b extends in the thrust direction L, R and drives two valves 6, 6.
The variable valve mechanism 90c of the third conventional example (Patent Document 3) shown in FIG. 10 includes two output members 93, 93 on both sides in the thrust direction L, R of the input member 92. A single connecting portion 93c connecting the two output members 93, 93 is provided radially outward of a tubular portion 92c serving as the swing center of the input member 92. The two output members 93, 93 drive two valves 6, 6.